This invention generally relates to electronic systems and in particular it relates to microphone bias current measurement circuits.
The current microphone of choice in the telecom industry is an electret microphone. This particular type of low cost microphone needs a bias current flowing through it to maintain proper operation.
Generally, and in one form of the invention, the microphone bias current detection circuit includes: a microphone circuit; an amplifier having a first output and a second output, the first output is coupled to the microphone circuit for providing a bias current to the microphone circuit, the second output provides a sampled current proportional to the bias current; a first switch having a first end coupled to the second output of the amplifier; a resistor having a first end coupled to a second end of the first switch; and a second switch coupled between the first end of the resistor and a reference current source.